Aircraft have power requirements which exceed the requirements for propulsion alone. In addition to propulsion, aircraft require power for avionics and thermal management, namely cooling systems. Many times the avionics require incoming air temperature below ambient which requires thermal management for proper function. In addition to thermal management and electrical power is required to drive many of the systems aboard an aircraft, including the avionics. Typically, electrical generation and thermal management are discrete systems within an aircraft. For each additional system, a weight and efficiency burden is placed on the aircraft.
Another burden accompanying electrical generation and thermal management systems is drag on the aircraft. As additional systems are provided more drag is produced. Drag could be reduced however by a smaller total package. In addition the aircraft would benefit from reduced weight. Additionally if propulsion, thermal management and electrical power generation could be packaged together, the resulting system would be highly beneficial to the overall efficiency of the aircraft.
Engines in current unmanned aerial vehicles (UAVs) are typically piston engines which have limited performance and no margin for auxiliary power take off. A lower output shaft speed from the prime mover requires a larger electric generator, resulting in increased drag. Additionally there is the concern of providing too much power resulting in waste.
Current practice does not involve a system approach to integrating propulsion, electrical generation and thermal management to an airframe from a single prime mover. Although the approach is counterintuitive, by providing a more powerful prime mover, an improvement in overall performance could be achieved. The aforementioned problems would be eliminated if the output from a single prime mover can be integrated into a system providing propulsion, electrical power generation and thermal management. Thus, a system approach to this problem would be desirable.